Over the past few weeks, Ive had to deal with a situation thats become all too common among those who comment on plaintiffs lawyers: the threat of a specious libel action.

Though such threats have never resulted in an actual lawsuit against me or my employer, the Manhattan Institute, other legal reformers havent been so lucky. A current and former colleague are involved in two such lawsuits, filed by the same plaintiffs lawyer, in Pennsylvania.

Former Illinois Appellate Judge Gordon Maag, after he lost a 2004 state Supreme Court election, filed two libel lawsuits, asking for damages of $100 million, against various tort-reform organizations.

While plaintiffs lawyers understandably know how to manipulate the legal system to attack their critics, they dont do so solely on their own behalf. Washingtonians have recently had their own front-row seats to the theater of libel litigiousness, as Redskins owner Dan Snyder filed a defamation action against the small Washington City Paper over a caustic article that criticized his teams management and past business practices.

And such lawsuits dont just target advocacy groups and media organizations: increasingly, ordinary citizens who criticize companies or public figures on blogs or social media face threats of litigation.

Even those familiar with First Amendment principles may be unaware of just how much harm such lawsuits can wreak. As a matter of substantive law, the U.S. erects high barriers against defamation litigation involving public figures.

The Supreme Court has long held that such lawsuits can create a “chilling effect” that inhibits free speech on matters of public import. To win a libel judgment in America, a public figure must show that a critic acted with “reckless disregard” for the truth.

Other countries afford far less protection, which is why Congress passed a law last August to prevent “libel tourism” -- foreign lawsuits against American authors and publishers that could compromise U.S. constitutional values.

But using libel law to chill public comment is sadly not limited to foreign jurisdictions. Even as the First Amendment protects against abusive libel lawsuits, such suits carry force in the United States because of two idiosyncratic features of American civil litigation.

First, civil defendants in the U.S. must submit to “discovery” -- disclosure of print and electronic documents, and mandatory “depositions” in which one is subjected to a lawyers intense questioning -- regardless of whether the facts support a plaintiffs claims.

Second, the U.S. is almost unique among legal systems in developed countries in that the loser of a lawsuit does not have to reimburse the winners costs.

Such rules create powerful pressures on those threatened with libel litigation, who face high costs to defend against a lawsuit even if they win.

Snyders attorney invoked just this calculus when he warned the owners of the Washington City Paper: “We presume defending such litigation would not be a rational strategy for an investment firm such as yours. Indeed, the cost of litigation would presumably quickly outstrip the value of the Washington City Paper.”

Several states and the District of Columbia have enacted special rules to deter so-called “Strategic Lawsuits Against Public Participation” (SLAPPs).

Strong forms of anti-SLAPP laws, such as Californias, stop the discovery process unless plaintiffs can show theyre likely to win, and award defendants their attorney fees whenever they ultimately prevail on the merits.

D.C.s new anti-SLAPP law is also strong, which is likely one reason why Washingtons own Snyder initially filed his lawsuit against a local paper in New York, based on the loose thread that the media company that publishes the periodical is indirectly owned by a New York hedge fund.

The potential for such forum-shopping across state lines, along with federal First Amendment values, makes a compelling case for a federal anti-SLAPP law. Rep. Steve Cohen, D-Tenn., who also sponsored last years libel tourism law, is now leading a bipartisan effort to pass the Protecting the Expression and Transmission of Ideas and Thoughts in Our Nation (PETITION) Act. Heres hoping he succeeds.